Search PubMed⌕ Search

Biomedical subjects

Bruno Giardina

Publications and source records attributed to Bruno Giardina.

66 records · Page 4Linked to original sources
PubMed2003

Analysis of the dynamics of cryoaggregation by light-scattering spectrometry.

Cryoglobulins are proteins that precipitate at temperatures below 37 degrees C. Cold-induced precipitation of proteins may occur in vivo secondary to several important diseases, and lead to pathological manifestations involving different organs. Cryoprecipitation may be observed in vitro by exposing serum samples, supposed to contain cryoglobulins, to low temperatures, but this needs several days to occur. Protein-protein interactions leading to cryoprecipitation are still poorly understood and the knowledge of the underlying mechanism may be relevant to the understanding of the onset of pathological manifestations. Using light-scattering spectrometry, we studied cryoprecipitation occurring in vitro at different temperatures and cryoglobulin concentrations. We describe the kinetics of the cold-induced precipitation of mixed cryoglobulins, measured as increase in turbidity. The plots obtained demonstrate that the cryoprecipitation did not occur as a single-step reaction, but consisted of four distinct phases where both temperature and cryoglobulin concentration affected the immune complexes formation. Light scatter spectrometry may provide a simple, sensitive and rapid method for the detection of cryoglobulins.

Chemistry, Clinical↗
PubMed2003

Dystroglycan and muscular dystrophies related to the dystrophin-glycoprotein complex.

Dystroglycan (DG) is an adhesion molecule composed of two subunits, alpha and beta, that are produced by the post-translational cleavage of a single precursor molecule. DG is a pivotal component of the dystrophin-glycoprotein complex (DGC), which connects the extracellular matrix to the cytoskeleton in skeletal muscle and many other tissues. Some muscular dystrophies are caused by mutations of DGC components, such as dystrophin, sarcoglycan or laminin-2, or also of DGC-associated molecules, such as caveolin-3. DG-null mice died during early embriogenesis and no neuromuscular diseases directly associated to genetic abnormalities of DG were identified so far. However, DG plays a crucial role for muscle integrity since its targeting at the sarcolemma is often perturbed in DGC-related neuromuscular disorders.

Animals↗
PubMed2002

Band-3 protein function in human erythrocytes: effect of oxygenation-deoxygenation.

Sulfate transport by band-3 protein in adult human erythrocytes was shown to be modulated by oxygen pressure. In particular, a higher transport activity was measured under high oxygen pressure than at low one (0.0242+/-0.0073 vs. 0.0074+/-0.0010 min(-1)). Other factors, such as magnesium ions and orthovanadate, which can indirectly affect the binding properties of the cytoplasmic domain of band 3 (cdb3), influence significantly the anion exchanger activity. No effect of oxygen pressure on sulfate transport was found in chicken erythrocytes, which may be related to their lacking the cdb3 binding site. These findings are fully consistent with a molecular mechanism where the oxygen-linked transition of hemoglobin (T-->R) could play a key role in the regulation of anion exchanger activity.

Animals↗
PubMed2002

O(2)-dependent stimulation of the pentose phosphate pathway by S-nitrosocysteine in human erythrocytes.

In the present study we analysed the effects of S-nitrosocysteine (CysNO) on adult human red blood cell metabolism and observed that metabolic response depended on the degree of cell oxygenation. In particular, glucose metabolised through the pentose phosphate pathway (PPP) was higher in treated erythrocytes than in untreated cells only at high O(2) pressure. Since, following the treatment of intact cells with CysNO, glucose-6-phosphate dehydrogenase (G6PD) and phosphofructokinase (PFK) activities did not evidence any significant alteration, the possibility that the stimulation of PPP was triggered by a CysNO mediated modification of these enzymes was excluded. Intracellular S-nitrosoglutathione (GSNO), detected only in treated red blood cells, may be linked solely to the exposition to the NO donor. A possible rationalisation of the different metabolic behaviour shown by erythrocytes as a function of their oxygenation state is proposed. It takes into account the different route of catabolic degradation observed in vitro for GSNO under aerobic and anaerobic condition.

Cysteine↗
PubMed2002

Serum folate and homocysteine levels in head and neck squamous cell carcinoma.

BACKGROUND: Local and systemic metabolic alterations are always present in cancer. Carcinogenesis is associated with biochemical disorders, often nonspecific, that might promote or derive from tumoral progression. Thus, analysis of metabolic alterations may be a valuable approach to understanding the biochemistry of tumors and may provide a means of identifying new targets for therapy. The methionine cycle in particular has been extensively studied in human cancer. METHODS: The authors analyzed serum concentrations of two metabolites of such pathways, folate and homocysteine, in 42 patients affected by head and neck squamous cell carcinoma (HNSCC) in comparison with two control groups, composed of smokers and non smokers. RESULTS: Mean folate level was 5.8 +/- 2.1 ng/mL in carcinoma patients, 9.1 +/- 2.7 ng/mL in smoking controls, and 9.7 +/- 2.2 ng/mL in non smoking controls, with a statistically significant difference between carcinoma patients and smokers (mean difference: -3.3 ng/mL; 95% confidence interval [CI]: -4.234 to -2.366; P < 0.0001) and between carcinoma patients and non smokers (mean difference: -3.9 ng/mL; 95% CI: -4.67 to -3.13; P < 0.0001). Mean total homocysteine level was 10.4 +/- 5.3 microM in carcinoma patients, 7.8 +/- 2.5 microM in the non-smokers' group, and 8.3 +/- 2.8 microM in the smokers' group, with statistically significant differences between carcinoma patients and smoking controls (mean difference: 2.1 microM; 95% CI: 0.7056 to 3.494; P = 0.0034) and between carcinoma patients and non smoking controls (mean difference: 2.6 microM; 95% CI: 1.381 to 3.819; P < 0.0001). CONCLUSIONS: Differences in serum levels of folate and homocysteine might arise from tumor development and consequent metabolic alterations or might precede and promote tumor progression. If hypofolatemia is a risk factor for head and neck carcinogenesis, it might suggest a role for folate as a novel chemopreventive agent both in patients with precancerous lesions and in patients with treated HNSCC at risk for loco-regional recurrence and second primary tumors.

Adult↗
PubMed2002

The effect of anions on azide binding to myoglobin: an unusual functional modulation.

The effect of increasing concentrations of several anions on the azide (N(-)(3)) binding properties of sperm whale and horse ferric myoglobin has been studied. Surprisingly, a number of anions may act as heterotropic effectors, decreasing the affinity of myoglobins for N(-)(3), in the following order: ClO(-)(4)=I(-)>Br(-)>Cl(-) and SO(2-)(4), which mirrors the increase in their charge density. The largest effects were measured using ClO(-)(4) and I(-), which produce a 4-fold and 8-fold reduction of the N(-)(3) binding affinity in horse and sperm whale myoglobins, respectively. A dissociation equilibrium constant (K(d)) ranging from 150 to 250 mM was estimated for ClO(-)(4) and I(-) binding to myoglobins. In order to analyse the molecular mechanism producing the reduction of the N(-)(3) binding affinity to ferric myoglobin, the potential anionic binding sites within ferric myoglobin were investigated by a molecular modelling study using the program Grid. Analysis of the theoretical results suggests two particularly favourable binding sites: the first, next to the distal side of the haem, whose occupancy might alter the electrostatic potential surrounding the bound N(-)(3); the second, involving residues of helices B and G which are far from the haem iron atom, thus implying a long range effect on the bound N(-)(3). Based on the evidence that no significant conformational changes are found in the three-dimensional structures of N(-)(3)-free and N(-)(3)-bound myoglobin and on previous results on N(-)(3) binding to ferric myoglobin mutants in CD3 positions, we favour the first hypothesis, suggesting that the functional heterotropic modulation of monomeric myoglobin is mainly depending on a decrease of the positive charge density induced by the binding of anions to the haem distal side.

Allosteric Regulation↗
PubMed2002

Comparing different methods for homocysteine determination.

Slightly elevated values of homocysteine are commonly associated with thromboembolic diseases, while high values can be found in patients with congenital metabolic defects or nutritional problems. The clinical use of homocysteine as an independent marker of cardiovascular disease was limited in the past by technical problems with its measurement, the instrumentation (HPLC, radioenzymatic assays, gas chromatography-mass spectrometry, etc.) and the necessary skills required. Commercially available immunoassays now permit a simpler and more rapid measurement of homocysteine, that is more suitable for routine clinical laboratories; in this paper we analyze the results obtained by using three fully automated methods for homocysteine determination (Abbott IMx immunoassay, Abbott AxSYM immunoassay and Immulite 2000 homocysteine immunoassay) and their correlation with the widely used HPLC method. The results clearly indicate that all three automated immunochemical methods correlate well with the HPLC method (slope 0.97-1.03; intercept 0.95-1.91 with a recovery above 95% for all three methods).

Adolescent↗
PubMed2002

Early increase of oxidative stress and reduced antioxidant defenses in patients with uncomplicated type 1 diabetes: a case for gender difference.

OBJECTIVE: Diabetes increases the risk of coronary heart disease (CHD) to a greater extent in women than in men. We investigated whether type 1 diabetic patients with short duration of disease and without complications have an altered oxidative status and whether there are differences between men and women. RESEARCH DESIGN AND METHODS: We investigated oxidative status in 29 control subjects and 37 patients with uncomplicated type 1 diabetes with duration of 6 +/- 3 years. RESULTS: Compared with control subjects, type 1 diabetic patients had lower total plasma antioxidant capacity (TRAP) (720.3 +/- 111.2 vs. 972.5 +/- 97.7 micromol/l in men, P < 0.001; 579.8 +/- 95.4 vs. 930.1 +/- 84.2 in women, P < 0.001), higher lipid hydroperoxide (ROOH) levels (6.4 +/- 2.2 vs. 2.0 +/- 0.7 micromol/l in men, P < 0.001; 8.1 +/- 1.9 vs. 2.2 +/- 0.6 in women, P < 0.001), higher total conjugated diene (CD) levels (0.037 +/- 0.003 vs. 0.033 +/- 0.002 A.U. in men, P < 0.001), lower 246-nm CD levels (0.0032. +/- 0.0010 vs. 0.0070 +/- 0.0012 A.U. in men, P < 0.001; 0.0022 +/- 0.0011 vs. 0.0072 +/- 0.0014 A.U. in women, P < 0.001), and higher 232-nm CD levels (0.0348 +/- 0.0041 vs. 0.0257 +/- 0.0022 A.U. in men, P < 0.001; 0.0346 +/- 0.0031 vs. 0.0246 +/- 0.0074 A.U. in women, P < 0.001). Compared with diabetic men, diabetic women had lower TRAP (P < 0.01), higher ROOH levels (P < 0.01), and lower 246-nm CD levels (P < 0.05). Plasma concentration of uric acid was significantly lower in patients with type 1 diabetes than in control subjects (3.3 +/- 0.3 vs. 4.3 +/- 0.2 mg/dl; P = 0.009) with a significant difference between women and men with type 1 diabetes (2.6 +/- 0.3 vs. 3.9 +/- 0.3, respectively; P = 0.009). CONCLUSIONS: Our findings suggest that reduced antioxidant activity and increased oxidative stress occur early after the diagnosis of type 1 diabetes, especially in women, and this might explain, at least in part, the increased susceptibility of diabetic women to cardiovascular complications.

Adult↗
PubMedDate not supplied

Alteration of monocytic cell oxidative burst caused by methacrylic monomers present in dental materials: a chemiluminescence study.

Methacrylates are present in dental composite resins used in clinical practice. Methacrylates are photo-polymerized, but this reaction is never complete, so release of uncured monomers in the periapical tissues and in biological fluids may happen and, potentially, alter the repair of pulpal and of periapical lesions by interfering with local phagocytes. The aim of this study was the evaluation of the functional activity of the monocyte-macrophage system after incubation with methacrylic monomers. The oxidative burst of two cellular systems was analysed using the chemiluminescence technique. Data were collected and statistically analysed. Monomers were found to reduce the in vitro oxidative burst of phagocytes independently from their cytotoxicity. These findings demand further evaluation of the effects of oxidative burst alteration in monocyte-macrophage function and may prompt the inclusion of the described chemiluminescence test in biocompatibility preliminary studies of dental materials.

Cell Survival↗
PubMedDate not supplied

Characterization of the human salivary basic proline-rich protein complex by a proteomic approach.

Thirteen samples of human normal whole saliva were analyzed by RP-HPLC-ESI-MS and MALDI-TOF-MS to investigate the basic proline-rich protein complex. Between known basic-PRPs the P-B, P-C (or IB-8b), P-D (or IB-5), P-E (or IB-9), P-F (or IB-8c), P-H (or IB-4), IB-6, II-2, IB-1, and IB-8a glucosylated were identified, whereas the II-1, IB-7, PA, and D1-A peptides were not detected. Some detected masses not attributable to known basic-PRPs were putatively ascribed to II-2 and IB-1 nonphosphorylated, II-2 and IB-1 missing the C-terminal arginine residue, and the 1-62 fragment of IB-6, named P-J peptide. A correlation matrix analysis revealed a cluster of correlation among all the basic PRPs (apart from the P-B peptide) which is in agreement with their common parotid origin.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Doxorubicin-derived metabolites induce release of cytochrome C and inhibition of respiration on cardiac isolated mitochondria.

BACKGROUND: The generation of doxorubicin metabolites other than semiquinone free radicals and mitochondrial dysfunction have been implicated in doxorubicin (DOX)-induced cardiotoxicity. This study examines pro-apoptotic mechanisms in isolated rat cardiac mitochondria exposed to DOX-derived cardiac metabolites i.e. doxorubicinol, doxorubicin aglycone and doxorubicinol aglycone. MATERIALS AND METHODS: Freshly isolated mitochondria were incubated in the presence of doxorubicin and its derivatives and the released cytochrome c was detected by Western blotting analysis. Oxygen consumption was measured with a Clark-type oxygen electrode and mitochondrial transmembrane potential (delta psi) was measured in a fluorometer in the presence of a fluorescent probe. RESULTS: The data obtained show that exposure of isolated mitochondria to the drugs determines a significant release of cytochrome c and a slight decrease in the mitochondrial transmembrane potential (delta psi). These effects are more evident when the experiments are performed in the presence of the aglycone derivatives. Moreover, an inhibition of the respiratory chain at the level of complex I is evidenced in the drug-treated mitochondria. CONCLUSION: The data obtained are consistent with the proposal that doxorubicin-induced cardiotoxicity may be partially exerted by the induction of programmed cell death, both directly and even more through its derived metabolites.

Animals↗